Cardiac pacemakers provide electrical stimulation to heart tissue to cause the heart to contract and thus pump blood through the vascular system. Conventional pacemakers typically include an electrical lead that extends from a pulse generator implanted subcutaneously or sub-muscularly to an electrode positioned adjacent the inside or outside wall of the cardiac chamber. As an alternative to conventional pacemakers, self-contained or leadless cardiac pacemakers have been proposed. Leadless cardiac pacemakers are small capsules typically including bipolar pacing/sensing electrodes, a power source (e.g. a battery), and associated electrical circuitry for controlling the pacing/sensing electrodes, and thus provide electrical stimulation to heart tissue and/or sense a physiological condition. The small capsule is typically fixed to an intracardiac implant site in a cardiac chamber with a fixation mechanism engaging the intracardiac tissue.
Accordingly, it is desirable to provide alternative structures to facilitate verification of sufficient engagement of the fixation mechanism into the intracardiac tissue to ensure the leadless cardiac pacemaker is secured to the intracardiac tissue.